This invention relates generally to portable light sources and, more particularly, to switches for portable light sources that are actuated through axial movement of the switch mechanism, or so-called push-button switches.
Flashlights and other portable light sources having pushbutton switches for opening and closing the electrical circuit between the lamp bulb and the source of electrical energy, typically batteries, are well-known. The ruggedness and reliability of such switches is particularly important because, in the case of most portable light source designs, if the switch fails it is not otherwise possible to illuminate the lamp bulb. Switch failure is one of the more common problems encountered with such devices. It occurs generally through malfunction of the mechanical movement of the switch mechanism or failure of the electrical contacts in the switch to make proper connection. In addition to being rugged and reliable, it is desirable that such switches have a relatively simple and inexpensive design, with components that are easily assembled to allow economical manufacture. Many prior pushbutton switches for portable light sources have not provided all these attributes.
Another concern of those involved in the design of portable light sources is preventing inadvertent operation of the switch to connect the electrical circuit when not desired. In the design of hand-held portable light sources, such switches are typically located in the handle (which in a common flashlight is its barrel or battery cell tube) so that the switch may be conveniently operated by the user's thumb while the handle is grasped in the palm of the hand. In order to diminish the risk of inadvertent operation, the switch may be recessed in the handle so that the pushbutton does not extend significantly above the handle surface.
In another type of portable light source, however, the pushbutton switch may be located where it is either undesirable or impractical to recess it. Such is the case, for example, with flashlights of the type having a pushbutton switch located in the tail cap of the flashlight. With such a flashlight, the user grasps the barrel in the palm of the hand so the thumb extends over the end of the barrel to depress the tail cap switch axially. In this orientation, the angle of the thumb does not readily permit depression of a recessed switch with ease. The pushbutton thus is designed to extend beyond the end of the barrel, but it is then susceptible to being inadvertently switched on or off. There is a need for a switch for such applications which overcomes this problem and yet is still easy to operate.